Method of electrolytically producing manganese



July 15, 1952 F. w. WOODMAN ET AL 2,603,594

METHOD OF ELECTROLYTICALLY PRODUCING MANGANESE Filed May 15, 1947 INVENTORS FRANK W. WOODMAN & JAN MAX CROWELL I AM 7'" 4W.

Patented July 15, 1952 2,603,594

'UN TEDYYSTATE PATENT F C I METIlOD F ELECTROLYTICALLY PRODUCING MANGANESE Frank W. Woodman, Maplewood, La., and Jan M. Crowell, Brisbane, Calif., assignors to Vanadium Corporation of America, New York, N. Y., a cor- I notation of Delaware ApplicationMay 13,1947, Serial No. 747,672 r f provem'ents in methods and apparatus for producing electrolytic manganese. The present application is a continuation-impart of our appliammonium sulphate need not be employed This invention relatestto new and useful :im-

' GClaims. (01; 204-105) Successful and economical deposition of, manganese from solutions. mustibe carried'out under very carefully controlled oonditions in'which for best results'the .pH value, concentration of mancation SerialNo. 439,530 filed April 18, i942, now 5 ganese and thetemp'erature are regulated acb d d, i i cording to the current densityusedn In the accompanyingdrawings: The reactions occurring in the manganese elec- Figure l'ill ustrates, in'a diagrammatic manner, trolytic cell are as follows: e 11 fol: electro-depositmg m n ane aqco Anode i ns;

gmg to pr1or known methods; 1o 1 f "Figure 2 illustrnts, in a diagrammatiomanner, (1) 2 I-I O=O H J f a cell for electrodepositing manganese according SO'4+O2;MnO2 -j- SQ4 to'our method; and (3) 2H+SQ4=H2SO4 Figure 3 is a perspective view of one of the Cathode racfions':

n in- 1 ii g ii tim 9 e cell Show F g 15 (4) MI1 SO 4=MN+SQ4 In the electrodepos'ition of manganese from v (5) aQ= e+ OH platable manganese solutions, p i p ul- 5 jg s i Dhate d chloride 19 1 3 n li d; Manganese metal possesses. a very low hydroh u a Solution m e y si ns 20 gen overvoltage; 'Therefore thepI-I value of the u ph e, but manga es Sulphate 8911113011 solution surrounding the cathode must be carenot be emplo e alone because immediately upon fully regulated as otherwise, i'e-solution of the depositing out some of the manganese, the soludeposited manganese by the sulphuric aidigem tion becomes alkaline around thecathode and elated at the anode w uld o c 'p v t due to t 1k 1i o dition,basic-hydr 2 the acid at the anode from vcoming in. eon-tact m n ane e saltsp e ipi Theprinclpal Salt with the manganese 'metal'deposited on the oathis believed'to be man n hydroxide nd Where ode, a diaphragm is interposed between the two this term is used in this specification it is intended electrodea 1 j to; include all such basic hydra ed c m Interposing the diaphragmbetweenthe elec- For this reasonithe man ane sol t qnra trodes presents a major problem, i. e.,-control of has'ammonium u ph added o E P 9 Ferves the catholyte pH. It is well known that manganese the purpose of preventing the p p 3 Q of in alkaline solutions. willprecipitate as' the hyman anese hydroxide. The e gm 9 the droxide and,if such precipitation occurs around sol ti the greateris e n y q n the cathode, it will: contaminate the manganese hydroxide to p cipitate. orq l t deposit andwill' eventually cause the deposition h gh pH'i a solutionsarejvemployedi 1t 15 of metallic manganese to cease Ammonium necessary to employ r l tively 343 am u s sulphate is used inorder to protect the cathode ammonium sulphate 0 p ntt s obleqtlqnable manganese from precipitated manganese hydroxpr c pitati nof m n n s dre es 1m11aflyide because ammonium sulphate will prevent its on m Chloride m befemployed F 40 precipitation. although-the hydroxide may be ganesefiohloridebaths to prevent the p qm present in solution, ,The, amount of ammonium tion of man a Y de- V sulphate in solution which isfrequired to prevent "The e1ectro 'p n 0f mangamse Pres a the precipitation of manganese hydroxide .j'dedistinctly difielent problemifmm.'ihatrmvolvsd pends on the pH of jthesolution in the cathode in l d o n e ein' m al Where compartment, The hig'herthe'pHJ of the oathcompartment cells may'beneficianybe u i Such olyte, the more ammonium sulphate is required as cadm l O I i k a (1983 and viceyersa. I A 7 3 not have. ,the'objecfiQnable P r of i m fi i Heretofore, in' the electrodeposition of manhydrateddx d syandaccording y h 39: ganese the practice has been to place eachiindeposition-of nic elfi 0 it is P V Qe dividual cathode in a;compartment witha dias'ar y to empl y a mo a e alone with Y 1 phragm asan' integral part-thereof (see Electronickel sulphate. Thus in depositing nic n0 l'ytic Manganese, JtfKoster e't' ali, Engineering & problem is involved as to-the relative proportions Mining "Journalpvols 137, page 510); When a of nickel s lphate and ammonium sulphate; since cathode is surrounded by a relatively small 'diaphrag'm, the volume of-solutioncontained around each cathode is small and is therefore subject to radical changes in pH value, concentration of manganese, and temperature. For this reason, in carrying out the electrodeposition of manganese in accordance with prior methods in which the cathodes -.were :ienclosed in diaphragms, it was essential that the ammonium sulphate concould be accomplished by the previous practice, since the cathode compartment is a single body. In one example of commercial practice according to the old method (see Fig. l), 27 cathode compartments designated by reference numeral 6 were employed. Since eachv cathode compartcentration of the catholyte be kept at a relatively Q high amount in order to insure the presence of suificient ammonium sulphate to largely prevent the precipitation of manganese hydroxide when the pH of the catholyte fluctuated widely.

Fig. 1 illustrates in a diagrammatic manner the previously used method of electrodeposi-ting manganese where the individual cathodes were surrounded by diaphragms. In this, figure, tank 2, containing a solution 3 of manganese sulphate and ammonium sulphate is provided with altervarying conditions obtaining in thesmall catholyte compartments. A further objection to the old methodwas that the catholyte f-eed'to each compartment (being small in amount) was not uniform, and therefore resulted in. variable electrodeposition. Another 'diiiiculty was, encountered in removing and replacing the cathode in the cathode compartment during the stripping operation. During the electrodeposition process a certain amount of salting occurs in the cathode compartment due to'the'usual limited precipitation-in the cathode compartment of manganese hydroxide. The manganese hydroxide settles to the bottom of the cathode compartment and conta'cts'the lower portion of the manganese which has been deposited and contaminates the deposit as well as causing. re-solution of the already deposited metal.

In accordance with our invention we place each of the individual anodes within a compartment and suspend the anodes so compartmented in an electrolytic tank between cathodes; freely suspended in the tank." This system has certain very valuable features and; is illustrated diagrammatically in. Fig. 2. As shown therein, a tank containing an electrolyte H is provided with a plurality of alternately arrangedanodes l2 and cathodes [3. Each oftheanodes is surrounded by a diaphragm I 5, whereas the cathodes are freely suspended in a. single. body of solution l of largev volume .asconipared with the volume of any individual anode compartment [4. The catholyte compartment may befed by a single feed indicated by the reference; numeral It, as contrasted with the large number ofsmall feeds 1 required in the arrangement shown in Fig. 1. p V V The arrangement shown in Fig. 2'allows 'a plurality of cathodes to be suspended in one relatively large body of catholyte, to which cath-' olyte may be added fresh cell feed through one or more ports. These ports may be controlled automatically by floats or other known liquidlevel apparatus much more expeditiously than ment was divided in two by the cathode, this in effect meant that the cell contained 54 separate cathode compartments, each requiring an individual feed; By reference to Fig. 2 it will be seen that the entire cell may be fed by a single feed i 6 since the catholyte forms a single body. This single body is ofvery large volume compared with any one of the individual compartments I4,

and accordingly conditions in the catholyte compartment l5 maybe very accurately controlled. Another advantage of the arrangement shown in Fig, 2 is that the removal and replacement of the cathodes during stripping operations is facilitated. placed in grooved guides within the. cathode compartment frames. The electrodeposited metal sometimes wedged the. cathode into the frame and the removal of. the cathode damaged either the cathode, the frame, or both. These disadvantages are overcome inthearrangement according to Fig. 2, in which. the cathodes are freely suspended in the catholyte, l5.

The replacement of eachcathod'e in its frame had to. be-under delicate controland had. to be done manually. With. th'e'arrangem'ent shown in Fig. 2, however, the cathodes can be removed and replaced in the tank mechanically because they do not have to be inserted in grooved frames in the tank but are simply suspended in the catholyte. A uniform catholyte composition is maintained around. each cathodewhere.formerly there were twice as many'catholyte compositions to.

control as there were cathodes.

As previously stated, manganese hydroxide tends to precipitate 'fromIalk-aline' solutionsat thecathode and according to prior practiceit has been necessary to employ large amounts. of ammonium sulphate .to largely prevent this precipitation. v amounts of ammonium sulphate to cover wide fluctuations in pH and other conditions which occurred in cathode compartments. of small volume. It will be seen that in. the new arrangement shown in Fig. 2, the catholyte compartment. [5 is of large volume as'compared with the individual anodecompartments I4 and. for this reason the pH value andotherconditions of. the catholyte can be accurately ..eontrolled. Since there are no wide variations inthe pH and other conditions of the catholyte, the. amount of ammonium sulphate added canloe. accurately adjusted to approximately thef quantity actually neededv to practically prevent precipitation of manganese hydroxide. .Such limited, amount of precipitate as cannotbepreyented accumulates at the bottom of the tank. out ofcontact with the cathodes and isreadily removable as contrasted with accumulationagain-st the cathode at the bottom of the diaphl'agm as'in Fig. 1. This means that less ammonium sulphate is required in the catholyte. -It is to be noted that the. solution fed to a manganese electrolytic cellis saturated with respect to manganese sulphate and ammonium sulphate. Therefore, since less ammonium sulphate isrequired in the catholyte, the

concentration of ammoniumsulphatein-the--feedv can be decreased and the concentration of man- In previous practice the cathodes were It was necessary to employ large the cell feed result in higher concentrations of manganese in the catholyte which permits the employment of higher current densities while stil olyte tends to increase the hydrogen over-voltage on manganese. In the old arrangement shown in Fig. 1, in which the cathodes were surrounded by diaphragms, it was impossible to place cooling coils in the individual catholyte compartments because of the small space available. Accordingly, cooling coils were placed in the anolyte compartment and the cooling of the catholyte was dependent upon heat transfer from the oatholyte compartment through the diaphragm to the anolyte compartment. This was a very inefilcient way of regulating the temperature of the catholyte. In the arrangement shown in Fig, 2, however, there is sufiicient space in the catholyte compartment [5 for the reception of cooling coils which enable efficient cooling of the catholyte, whereby the efliciency of the electrodepositing e. g. 1% to 2.5%, of silver.

concerned with the support for or details of the cathode.

The anodes l2 are suitably supported within the anode frame, to be described, and are preferably formedof a material which will inhibit the formation of manganese oxide, examples of such anodes being: (A) an alloy containing about equal proportions of lead and tin and a relatively small proportion, e. g. 2% to 4% of cobalt; or (B) lead-silver anodes containin a small amount, Instead of using anodes which themselves minimize the formation of manganese oxide, we may employ lead anodes and introduce sulphur dioxide or other reducing agent into the anode compartments to prevent the formation of manganese oxide at the anodes. An installation in accordance with our invention would of course involve the usual arrangement of a plurality of cells, with suitable generator equipment, bus bars along-the cells, and connections to I anodes and cathodes, none of which we deem esoperation is substantially increased. By efll-' ciently cooling the catholyte, increased current densities have been made possible because increased current densities always are accompanied by more heat. Accordingly, the capacity of an electrolytic cell constructed in accordance with Fig. 2, having a large volume of catholyte and a small volume of anolyte is increased in two ways: (1) by increasing the current efficiency, and (2) by increasing the current density. The statement just made that the cell of Fig. 2 has a large volume of catholyte and a small volume of anolyte means, of course, that the catholyte has a volume greater than all of the anolytes combined.

During the electrodeposition of manganese the anolyte is more acid than the catholyte. It is necessary to prevent the more acid anolyte from diffusing into the less acid catholyte since otherwise the acid would dissolve the manganese which has been deposited. In the arrangement shown in Fig. 1 there is a large volume 8 of more acid anolyte and a small volume 9 of catholyte of higher pH. Thus the diffusion of the anolyte into the catholyte causes a substantial decrease in the pH of the catholyte. Referring to Fig. 2, however, the volume of more acid anolyte I4 is relatively small as compared with the volume of catholyte 45 of higher pH. Thus the diffusion of the anolyte into the catholyte does not cause any substantial decrease in the pH of the catholyte.

Referring now to Figures 2 and 3 of the accompanying drawings: 1

The cell proper comprises a tank ID of suitable acid-resistant material constructed in accordance with the customs usually prevailing in the electrolytic industries. These tanks are conventionally rectangularwith an open top, but having bottom, end, and side walls, one of the side walls, indicated by the reference character 19, appears in Fig. 2. One common practice is to fabricate the tanks of wood and line them with lead, butany suitable tank maybe used so far as our invention is concerned.

Cathodes l3, which'may be formed of any suitable metaLsuch as stainless steel or aluminum, are conventionally provided with wooden strips around their edges in order to eliminate the well known edge effect of electrolytic deposition. Our invention, however,- is not-primarily sential to bring out clearly the details of our invention.

An anode frame I4 is shown in Fig. 3. The anode frame comprises cross pieces 18 which bridge the tank In and rest upon the upper edges of the tank sides IS. The frame has a bottom 20 and two side frame members 2| made of wood. A diaphragm I42. is supported on either side of the anode frame and is of suitable character for the purpose at hand. The diaphragm may be closely woven cloth such as heavy duck or canvas or in general any porous or semi-porous septum material which will permit migration of ions between the catholyte and anolyte. Shelton in Patent 2,119,560 and Koster et a]. in'Electrolytic Manganese, Engineering 8: Mining Journal, vol, 137, page 510, discuss suitable types of diaphragms for use in electrodepositing manganese. Thus it will be seen that the anodes are separately completely enclosed in a compartment, the walls of which comprise essentially a diaphragm, and the cathodes are all in one catholyte compartment comprising the entire remaining portion of the electrolytic tank.

In the operation of the cell, the cell feed is delivered continuously to the cathode compartment l5 through a pipe l6; Suitable valve means (not shown) may be provided to control the flow. Preferably the level of anolyte is kept only slightly below the level of the catholyte by suitably continuously withdrawing the anolyte from the separate compartments by suitable means, for example, by gravity through an overflow vent and drain line 22 at the same rate as platable manganesesolution is fed to the tank It). The catholyte flows to the anolyte compartment because of the lower hydraulic head by seepage, percolation, diffusion, or dialysis through the diaphragm, or vents such as those shown at 23 in Fig. 3 may be used to provide for direct liquid flow between the two compartments. It will be seen that the catholyte flows directly into the individual anolyte compartments while all of the catholyte is maintained in the tank I0; Thus the catholyte at no time has access to air in amounts sufllcient to form an appreciable quantity of basic hydrated manganese salts in the catholyte. The flow of catholyte within the tank isin a relatively quiescent manner, as can be seen from the fact that the catholyte merely seeps through the diaphragm into the, anolyte compartments or flows through the port 23 which is located only at a slightly higher level than the vent 22 and accordingly there is notsufficientagitation of the catholyte to cause the air which contacts the surface of the catholyte to form an appreciable quantity of basic hydrated manganese salts in the catholyte. I v

The details of construction of the cell are not of prime importance in the practice of our invention. and the cell details as shown may be modified extensively within the scope of our invention. Any usual means for supportingthe anodes and cathodes in the tank, and connecting them into the electrical circuit, may be employed. In general, this may involve the use of negative and positive bus-bars at opposite sides of the cell, with anode and cathode bus-bars running transversely of the cell, and connected to (and inmany installations supported at one side by) the'positive and negative bus-bars, respectively. As a rule the ends oi the anode and cathode bus-bars opposite to those engaging the positive and negative bus-bars are supported by the opposite top edge of the tank. This usual construction or other suitable construction for supportin the anodes and cathodes may be used with our invention, but this has not been shown in the drawing since it is not a part of our invention. We merely wish to point out that our invention is adapted for use with any usual types of installation with little or no change except in so far as the diaphragm arrangement is concerned.

The following are examples illustrating the results obtained according to previously known methods and other examples illustrating our inyention. Example 1 is illustrative of results obtained according to prior investigators as reported in Bureau of Mines Report of InvestigationsR. 1-34.06, by S. M. Shelton and others,

Example 1 The cell contained alternately arranged anodes and cathodes, each cathode being enclosed in an individual diaphragm. The feed solution consisted of 200' grams per liter of ammonium sulphate, and 25grams per liter of manganese. The catholyte contained about grams per liter, of manganese and had a pH of 9 -9.2. The plating was done at acurrent density of 18-20 amps. per sq. it. 'at a temperature of about 31 C. The cur- :rentetfi'ciency was about 50 Earample 2 v Example 2 illustrates the present invention. The plating tank contained alternately arranged anodes and cathodes, each anode being enclosed in a diaphragm; the anodes were lead-silver anodes and the cathodes were chromium-containing steel. The feed solution contained 171 grams per liter of ammonium sulphate and 42.3

grams per liter of manganese. This is a ratio by 7 weight of about 4.0 parts of ammonium sulphate to l partof manganese. The catholyte had a pH value between 6.5 and 7.0 and contained 25 grams or manganese per liter. The current density ranged from 40 tov 70 amps. per sqnft. and the current efiiciency was between 60.2% and 64%. The strip was 17.3 grams per liter of manganese.

Example 3 This examplealsof is illustrative of our invention,.each anode being enclosed in a diaphragm.

The 'feed solution contained 130-135 grains per' liter of ammoniumsulphate and'3 5 grams per liter of. manganese. This is a. ratio by weight of manganese." The catholyte contained 13 grams about 3.7 partsof ainmonium sulphate to 1 part per liter of manganese and had a pH of 8.2-8.4. The plating was done at a cathode current'density of 45-50 amps. per sq. ft. with a resulting currentefiiciency ranging between about 60% and 65%. 4

The advantages of our process can be seen from a comparison of Examples 2 and 3 (which illustrate our process), with Example 1 (which is illustrative of the prior art). In our examples, current densities from 40 to amps, per sq. it. were employed as contrasted with current densities of 18 to 20 amps. per sq. ft. in the prior practice. In our process the concentration of manganese in the catholyte was from 13-25 grams per liter as compared with 10 grams per liter in Example 1. In our examples, 17 to 22 grams of manganese per liter were stripped as compared with 15 grams per liter in Example 1. The current efiiciency in our examples was from 60% to 65% as contrasted with a current eificiency of about 50% in Example 1.

In carrying out our process, the current density may be as low as 18 amps. per sq. ft. or as high as 275 amps. per sq. it. As the current density increases, the current efiiciency generally decreases. The preferred current density is between 40 and 70- amps. per sq. ft. The pH may be between 2 and 9.2 but preferably is between 6 and 8.5. The manganese concentration in the catholyte may be between 8 and gram per liter. The feed solution may contain between 25 and grains per liter of manganese and between 25 and 200 grams per liter of ammonium sulphate.

The invention is not limited to the examples but may be otherwise embodied within the scope of the following claims.-

We claim:

1. The method of electrolytically producing manganese metal, which comprises providing a body of platable manganese solution in a tank, continuously feeding a platable manganese solu tion to said body, passing a current of about 18-275 amperes per square foot between anodes and cathodes arranged in said body to cause manganese metal to plate on the cathodes, separating each anode from the cathodes by an individual diaphragm of such porosity that ions can migrate therethrough so as to provide a plurality of individual anolytesand a single catholyte having a volume greater than all of the anolytes combined, flowing the catholyte directly into the individual anolytes while maintaining all of the catholyte in the tank, and continuously withdrawing anolyte from the individual anolytes.

2. The method of: electrolytically producing manganese metal, which comprises providing a body of platable manganese solution in a'tank, continuously feeding a platable manganese solution to said body, passing a current of 18-275 amperes per square foot between anodes and cathodes arranged in said body to cause manganese metal to plate on thecathodes, separating each anode from the cathodes by an individual diaphragm of such porosity that ions can migrate therethrough so asto provide a plurality of individual anolytes and a single catholyte having a volume greater than all of the anclytes combined, flowing the catholyte directly into the individual anolytes while maintaining all of the catholyte in the'tank. and continuously withdrawing anolyte from the individual anolytes at the-same rate as platable manganese solutionis fed'to said body. 7

3.. The :method of electrolytically producing body of platable manganese solution in a tank.

continuously feeding a platable manganese solution to aid body, passing a current of 18-275 amperes per square foot between anodes and cathodes arranged in said body to cause manganese metal to plate on the cathodes, separating each anode from the cathodes by an individual diaphragm of such porosity that ions can migrate therethrough so as to provide a plurality of individual anolytes and a single catholyte having a volume greater than all of the anolytes combined, flowing the catholyte directly into the individual anolytes while maintaining all of the catholyte in the tank and while preventing access of air in amounts sufficient to form an appreciable quantity-of basic hydrated manganese salts, and continuouslywithdrawing anolyte from the individual anolytes.

4. The method of electrolytically producing manganese metal, which comprises providing a body of platable manganese solution containing ammonium sulphate and manganese sulphate, continuously feeding to said body a platable manganese solution containing about 25-200 grams per liter of ammonium sulphate and about 25-100 grams per liter of manganese, passing a current at a current density of about 18-275 amperes per square foot between anodes and cathodes arranged in said body to cause manganese metal to plate on the cathodes, separating each anode from the cathodes by an individual diaphragm of such porosity that ions can migrate therethrough so as to provide a plurality of individual anolytes and a single catholyte having a volume greater than all of the anolytes combined, flowing the catholyte directly into the individual anolytes while maintaining all of the catholyte in the tank, and continuously withdrawing anolyte from the individual anolytes.

5. The method of electrolytically producing manganese metal, which comprises providing a body of platable manganese solution containing ammonium sulphate and manganese sulphate, continuously feeding to said body a platable manganese solution containing about 25-200 grams per liter of ammonium sulphate and about 25-100 grams per liter of manganese in a ratio by weight of about 3.7 to 4 parts of ammonium sulphate to 1 part of manganese, passing a current at a current density of about 18-275 amperes per square foot between anodes and cathodes arranged in said body to cause manganese metal to plate on the cathodes, separating each anode from the cathodes by an individual diaphragm of such porosity that ions can migrate therethrough so as to provide a plurality of individual anolytes and a single catholyte having a volume greater than all of the anolytes combined, flowing the catholyte directly into the individual anolytes while maintaining all of the catholyte in the tank, and continuously withdrawing anolyte from the individual anolytes.

6. The method of electrolytically producing manganese metal, which comprises providing a body of platable manganese solution containing ammonium sulphate and manganese sulphate, continuously feeding tosaid body a platable manganese solution containing about 25-200 grams per liter of ammonium sulphate and about 25-100 grams per liter of manganese in a ratio by weight at about 3.7 to 4 parts of ammonium sulphate to 1 part of manganese, passing a current at a current density of about 40-70 amperes per square foot between anodes and cathodes arranged in said body maintained at a pH between about '6 and 8.5 to separating each anode from. the cathodes by an can migrate therethrough so as to provide a plurality of individual anolytes and a single catholyte having a volume greater than all of the anolytes combined, flowing the catholyte directly into the individual anolytes while maintaining all of the catholyte in the tank, and continuously withdrawing anolyte from the individual anolytes.

FRANK W. WO-ODMAN.

JAN M. CROWELL.

REFERENCES CITED The following references are of recordin the file of this patent UNITED STATES PATENTS OTHER REFERENCES Websters International Dictionary, 2d edition unabridged, page 2283, Merriam Co. (1940).

Bureau of Mines, Bulletin 463 (1946) pages 59, 60, 61, 62, and 63. 

1. THE METHOD OF ELECTTROYTICALLY PRODUCING MANGANESE METAL, WHICH COMPRISES PROVIDING A BODY OF PLATABLE MAGNANESE SOLUTION IN A TANK, CONTINUOUSLY FEEDING A PLATABLE MANGANESE SOLUTION TO SAID BODY, PASSING A CURRENT OF ABOUT 18-275 AMPERES PER SQUARE FOOT BETWEEN ANODES AND CATHODES ARRANGED IN SAID BODY TO CAUSE MANGANESE METAL TO PLATE ON THE CATHODES BY AN INDIVIDUAL DIAANODE FROM THE CATHODES BY AN INDIVIDUAL DIAPHRAGM OF SUCH POROSITY THAT IONS CAN MIGRATE THERETHROUGH SO AS TO PROVIDE A PLURALITY OF INDIVIDUAL ANOLYTES AND A SINGLE CATHOLYTE HAVING A VOLUME GREATER THAN ALL OF THE ANOLYTES COMBINED, FLOWING THE CATHOLYTE DIRECTLY INTO THE INDIVIDUAL ANOLYTES WHILE MAINTAINING ALL OF THE CATHOLYTE IN THE TANK, AND CONTINUOUSLY WITHDRAWING ANOLYTE FROM THE INDIVIDUALL ANOLYTES. 